MITSUBISHI ELECTRIC FR-S520 - Manual (Page 151)

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3
(3) Warnings
Operation Panel Indication OL FR-PU04 OL
Name Stall prevention (overcurrent)
During
acceleration
If a current of more than 150% (* 4) of the rated
inverter current flows in the motor, this function
stops the increase in frequency until the overload
current reduces to prevent the inverter from
resulting in overcurrent shut-off. When the
overload current has reduced below 150%, this
function increases the frequency again.
During
constant-
speed
operation
If a current of more than 150% (* 4) of the rated
inverter current flows in the motor, this function
lowers the frequency until the overload current
reduces to prevent overcurrent shut-off. When the
overload current has reduced below 150%, this
function increases the frequency up to the set
value.
Description
During
deceleration
If a current of more than 150% (* 4) of the rated
inverter current flows in the motor, this function
stops the decrease in frequency until the overload
current reduces to prevent the inverter from
resulting in overcurrent shut-off. When the
overload current has reduced below 150%, this
function decreases the frequency again.
Check point Check the motor for use under overload.
Corrective action
The acceleration/deceleration time may change.
Increase the stall prevention operation level with Pr. 22 "stall
prevention operation level", or disable stall prevention with
Pr. 21 "stall prevention function selection".
Check that the torque boost (Pr. 0) setting is not higher than
required.
*4. The stall prevention operation current can be set as desired. It is factory-set to
150%.
Operation Panel Indication oL FR-PU04 oL
Name Stall prevention (overvoltage)
Description
During
deceleration
If the regenerative energy of the motor increases
too much to exceed the brake capability, this
function stops the decrease in frequency to prevent
overvoltage shut-off. As soon as the regenerative
energy has reduced, deceleration resumes.
Check point Check for sudden speed reduction.
Corrective action
The deceleration time may change. Increase the deceleration
time using Pr. 8 "deceleration time".